Effects of the magnetic field on the freezing parameters of the pork

In this study, we investigated the effect of the different magnetic field type and intensity on the freezing process of pork samples. The permanent magnetic field (PMF) and the alternating magnetic field (AMF) with the intensity varied from 0.00 mT to 16.00 mT and 0.00 mT to 1.80 mT respectively were applied on the pork samples when they were freezing to -30 °C at the freezing rate of 4 °C/min. Five parameters including the nucleation temperature, freezing temperature, time through -1 °C to -5 °C, phase change time and subcooling time were chosen to evaluate the freezing effects. The results showed that all the freezing parameters except the freezing temperature were significantly different with PMF (p < 0.05). The nucleation point, phase change time and subcooling time decreased 2.79 °C, 1.76 min and 0.80 min respectively with the PMF intensity of 15.98 mT, while the time through -1 °C to -5 °C increased slightly. The nucleation temperature and time through -1 °C to -5 °C of the pork sample were not significantly different (p > 0.05) with AMF. The freezing temperature and phase change time decreased slightly and the subcooling time was similar to PMF. In addition, the whole freezing time was longer with AMF than PMF which would need more energy. So PMF may be a promising method for the higher food quality and less energy consumption. Take all the factors into consideration, 15.98 mT may be the optimal magnetic field intensity for PMF.